Rotary broom for street sweeper



Aug. 27, 1963 J. P. HORTON ETAL 3,101,501

ROTARY BROOM FOR STREET SWEEPER 2 Sheets-Sheet 1 Filed March 6, 1961MOUNTING PLAT J. P. HORTON ETAL ROTARY BROOM FOR STREET SWEEPER 2Sheets-Sheet 2 POSITIONING LUGS 6| ms; PLATE Aug. 27, 1963 Filed March6, 1961 Ute Stes Patent Ofice 3,191,501 Patented Aug. 27, 1963 3,101,501I ROTARY BROOM FOR STREET SWEEPER John P. Horton, 79 Old Fort Road,Bernardsville, N.J.; George E. Berry, Spring Run-Lanm-Maltinsville,N.J.;

and John E. Stirling, 1041 Wychw'ood Road, Westfield, NJ. Filed Mar. 6,1961, Ser. No. 93,558

7 Claims. (Q1. 15- -1 80) This invention relates to a rotary broom forstreet sweepers. f i I I Rotary brooms are often used as side broomshaving a vertical axis of rotation in connectionwith a horizontallydisposed brush roller. The rotary broom'normall y serves to sweep thestreet dirt" from the gutter inward the assembly of this broom, theannular wire sections mento the roller brush which then ensures thefurther ,re- 1 associated with the provision of practicable brooms ofthis a type are quite dilferent from those associated with the provisionof small industrial brushes of the'same general shape. 7

In the conventional type of rotarybroom, the brush back is a circularplate, or ring, or ser-ies of circular segments which, in the vicinityof a periphery, provided with one or more circular series of holesextending therethrough having a square, ,or circular, cross section andextending obliquely outward in a direction corresponding to the desireddirection of the bristles in the finished rotary broom.' In each of theholes, a bunch of hair-pin shaped bristles is inserted from the rearside, or top side, of the brush back with its legs on either' side of apin or hinder wire extending across the holes: The bristles are securedonto the back by tightening a ring, or plate, toward-the rear, or top,side ofvthe brush back proper. (Such rings, or plates, are often anintegral part of the street sweeping machineon which the brushismounted). The bent portion of the bunches of bristles are'thus clampedbetween the additional plate and the pins or binder wire extendingtransversely'across the holes of'thebr'ush back and between the legs ofthe bunches of bristles. a f i The. manufacture of these known rotarybrooms very laborious and must, as far-as a substantialpart of theproduction is concernedg'be effected manually and consequently theproduction costs are very high. Also such a structure puts very heavystrain upoii'the'binder wire, it used, or the like. Any replacementof,worn brush material must be done manually and is likewise expensive,representing'an expense to the 'user comparable to the cost of anewbroom. U Since a'considerable time is required to remove worn and insertnew brush.

material, the user of the broom often feelsc'ompelled to keep sparebrooms on hand'in order to keep the sweepijng machines operating, thus'representing an increased eco-;

nomic burden. 1

Recently efforts have been made in Europe to overcome many: of theaforementioned defects of conventional rotary brooms forstreetsweepers.In accordance with oneembodiment, a rotary broom for street sweepers is.provided comprisinga circular, steel broom back having"a"frusto-conical, outwardlyfla're'd', steel ,flangej we'lded thereto andan annular section of] hair-pin'shaped wire bristles secured in aU-shapedring by'wire's andrelea'sably vcl'amped between the broombackand a circularsteel plate ring having an outer diameter onlyfslightly less f than the 'outer diameter of the inside base of the broombackilf for street sweepers, a continuous-layer of steel sweeper a ofbreakage of the broom back.

tioned above -is positioned between the frusto-conical broom back andthe clamping plate ring and, by means of a special assembly device, theclamping, ring is then forced in the direction of the, inside face ofthe broom back until the U-ring is firmly clamped between the clampingring and the inside face of the broom back. The ring plate is held inreleasable clamping relation by a plurality of threaded bolts extendingfrom the broom back through both the broom back and the clamping platering and held in clamping position by suitable, nuts tightly screwedonto the bolt threads. In this way, the annular V-shaped assembly ofbristles is forced downwardly in the direction, of the broom back andthe bristles are forced into contact with the frusto-conical flange andtherebelow to form a frusto-conical crown of brush material. Theclamping plate is provided with upwardly extending prongs which impedethe rotation of the U-shaped ring and brush material. During theassembly of this broom, the sides of the U-shaped ring are close andthereafter assist in securing the hair-pin shaped wires Considerableforce is required to bring the broom back and clamping I plate intocontact with the U-shaped ring.

H Iti-s a general object of this invention to provide a novel rotarybroom for street sweepers which preserves the advantages of the recentlydeveloped broom mentioned above whilebring-ing about certain otheradvantages. It is another object of the invention to provide a rotarybroom w'hich is especially easy to assemble and disassemble withorwithout-the use of special tools. It is an importantobject of thisinvention to provide a broom fora rotary street sweeper in which thebristles are'maintained in a vertical position during use so that thestiff but flexible bristles will exert a flipping action on stones orthe like when it comes in contact with such articles. It is a specialobject of the invention to provide arotary broom which-permits thoroughcleaning of street gutters by close approach to the curb without dangerIt is yet another special object of the invention to provide a rotarybroom in which the rotation of the brush element relative to thebrushback is inhibited. It is yet another object of this invention to provideindentation, or pockets, in the fru-sto- 1 conical brush crow-nthat willfacilitate a more effective rem-oval of larger objects, such as stones,from the gutter.

It is another important object of the invention to provide: a broom fora rotary street sweeper which willachieve' the above-mentionedobjectives Without overloading the Other objects and more detaileddescription which follows. I

i It now been found that an especially effective and especially easilyassembled and disassembled relatively light rotary broom of the lattertype disclosed abovecan be provided having a unitaryback and a unitarysection of annular brush material which can be releasably clamped. tothe brhsh back in such a way that the foregoing objectives can beachieved.

" The features of the improved rotary broomof'this in In-thefproductionof thistype of known rotary broom 'vention 'canbe best appreciated froma consideration at J the ggir'ob-lems "experien-ced 'in the us'e' o'fkn'own rotary; brooms for street sweepers, especially knowh rotarybrooms of the latter type mentioned above." lnlthe useg banish brooms,"it-ha's'been 'tound it is'extremely im'-" portant that the wire of thebrush section be held, not only originally but during operation, in asubstantially radial direction. It the wires are not so held, they tendto slant back away from the direction of rotation of the broom andconsequently lose a great proportion of the flipping action that is sodesirable for a satisfactory sweeping operation. Further-more, if thewires slant backwards, the vertical distance between the lipof thehousing of the broom back and the ground is decreased even though theremay be no wear on the brush wire and the life of the broom iscorrespondingly decreased. Thus both for better sweeping and longerlife, it is important to hold the broom wire in a radial posit-ion.

It has been found that the wires can be held in a radial position byproviding a downwardly extending portion of the brush back with inwardlyextending radial holding elements such as ribs or fins. These radialholding elements serve a plurality of additional 'functionsincludingreinforcing the broom back and a control of the wire down to the pointwhere it leaves the housing of the broom back.

Also in the use of brooms having a steel structure as described in theprior :art, it has been found that such materials add excessive Weightto the broom to the point of overloading the suspension system on thesweeper. This overloading also causes the broom to bear too heavily onthe street with a consequent excessive wear on the bristles. It appearsthat this difiiculty could be overcome by making the broom back and theclamping element out of a lightweight material. For practical reasons,aluminum casting-s were selected to achieve control over the Weightproblem. It was found that rotary broom backs made from aluminumcastings solved the weight problem but such brooms could not be attachedto the mounting plate of the rotor of a sweeper in the customary mannerby bolts-extending through the mounting plate and screwed into the backof the broom due to the fact that threads cut into the aluminum castingswere bound to deform and strip in use. disadvantage was overcome bydirectly casting threaded inserts into the aluminum casting made of hardand non-deformable metal such as steel. Where necessary, the steelinserts were provided with shoulders to prevent the insert from beingstripped out of the aluminum casting during use.

Likewise, by providing threaded steel inserts in the clamping element,it was found that the clamping element could be releasably clamped tothe broom back so as to hold the annular section of bristles in thebroom by bolts extending through the broom back and directly screwedinto these inserts. This procedure avoided the necessity for using boltswhich were held in clamping relation by nuts tightened onto the threadedend of the bolt as disclosed in the prior art. Such a prior artprocedure necessitates the .use of conventional locking means which werenot wholly satisfactory in use due to the tact that nuts tended toloosen during use of the broom. In accordance with this invention, ithas been found that the problem of such loosening can be eliminated formost installations. This desirable result is accomplished by therecessing of the bolts in the top of the broom back a distancecorresponding to the combined height of the bolt head and the washerused therewith. In this way, the bolt head is flush with the top of thebroom back so that when the broom is mounted on a conventional sweepermounting plate, the mounting plate covers the bolt heads and anytendency of the bolts to loosen in use is thereby prevented by themounting plate being directly in contact with the top of the bolt heads.V

In the use of gutter brooms containing trusto-conical flanges of theprior art, it has been found that careless use of the broom in theeffective cleaning of gutters may result in the outwardly extendingflanges of the broom back coming into contact with the curb whereby theflanges may be damaged or even broken. On the other hand, extreme carein avoiding damage to the broom by avoiding all contact with the curboften impedes eflective cleaning of the streets. Yet an outwardly flaredflange is desirable to properly position the bristles relative to theback of the broom. These problems have been overcome in the instantbroom by providing a brush back with a downwardly extending flangehaving an at least partially vertical outer wall and an outwardlytapering inner wall. By providing an outer wall at least having avertical section at its outermost periphery, greater bearing surfacesnormally provided by multiple point contact with the curb when thesweeping machine closely approaches the curb thereby lessening thelikelihood of damage, or breakage. Furthermore, due to the normaltilting of the rotary broom in the direction of the curb, any singlepoint contact of the outside surface of the broom back with the curbwill normally take place at a point removed from the outer periphery ofthe flange thereby lessening the leverage impact of such a contact.

'In the use of rotary brooms containing truev trustoconicalcrowns ofbrush material, as disclosed in the prior art, it has been found thatsuch brooms are not always effective in removing large articles, such asstones, which have a tendency to be tossed down the street ahead of suchbrooms rather than being swept in toward the center of the street wherethey can be removed by the horizontal roller sweepers. In order toovercome this difficulty, the broom back hereof have been provided withinternally extending protuberances, such as lugs, at the inside of thelower extremity of the downwardly extend-- ing flanges. These lugs, orthe like, cause circumferential inden-tions in the crown of the brushmaterial which have a tendency to catch stones and the like and throwthem away from the curb towards the horizontal roller sweeper.

Additionally, it has been found that the packaging, manipulation andassembly of the bristles which constitute the brush material used intherotary broom, and replacement of the brush material, can be greatlyfacilitated if p the brush material is pro-assembled into a unitaryflat, or

planar, annulus having its inner periphery fixedly positioned and boundas with a bonding material or a. metallic clamping element. For example,a very satisfactory brush tiller can be obtained from crimped wires ofthe type suitable for use in rotary brooms for street sweepers byplacing layers of such wires across the open jaws ofa U-shaped ring,forcing the central portion of the. wires downwardly into contact withthe inside base of the ring, as with binder wire, and thereafterhydraulically closing the jaws of the ring to force thewires into asubstantially flat annular section of brush material held in the ring bythe binder wire and the gripping effect of the closed jaws of the ring.This unitary annular wire filler may be easily packaged when shipped asa replacement and, easily clamped to the brush back by the owner of thestreet sweeping machine in the manner set out below.

Finally, it has been found that the brush material is more easilyassembled to form the rotary broom if a specially designed clampingelement is provided. It has been found that it is diflicult to assemblevery stiff wire bristles when the clamping element is of approximatelythe same diameter as the base face of the brush back as shown in theprior The clamping element is also prefer-ably made of aluminum castingprovided with threaded insets of harder material such as steel. Theclamping element is cast so that its structure complements thefunctioning of the unitary brush back in a manner which will be apparentfrom the more detailed description below. In a preferred embodiment theclamping element. constitutes asubstantially bell-shaped ring having aflat annular lower extremity of the bell-shaped portion assumesaposition in close proximity tothe radial fins of the broom back therebyfacilitating the holding of the bristles in a vertical position relative,to the broom back when th broom -is in use. 7 V .3 i The broom hereofmay be readily assembledbyplacing the clamping element on asupportingdevice and positioning the clamping ring of the assembled bristles. overpositioning lugs provided on the clamping element. Then the broom backis placed over the assembled bristles with the bolt holes thereof inalignment with the threaded inserts in the clamping element. Uponinserting the bolts and tightening them by screwing them intothe-threaded inserts inthe clamping element, the; inner peripherytofbrush material is-forced into releasableclamping relationship with theinside face of the broom back. By providing a clamping element-with anappropriate outer diameter in the region where it cpntactsthe innerregion of the annular brush material, the broom may be assembled withoutthe necessity for the use of a special tool. The required use of specialtools has obvious commercial disadvantages. Furthermore, the diameter ofthe clamping element where it first contacts the inner'region of thebrush material and the outward. taper to the inside of the flange of thebrush back may becorrelated so that upon assemblying the broom thecurvature impart-ed to the brush material does not place an-unduestresson the bristles and the bristles conform to thettaper over a largebearing area, In the use'of a true firusto-conical flange as shown inthe prior art, it is difficult to bring the bristles into contact withthe flange-over more than a limited area withoutputting undue stress onthe bristles. Under either circumstance, the useful life of the bristlesis importantly lessened. H t 1 plhe invention is more fully explained inthe following description referring to the accompanying drawingsrepresenting a specific illustrative embodiment of the improvedrotarybroom, in which Y a I j s 1 FIG. l showsa fragmentary vertical {,CIOSSsectional view of an-assembl ed,broorn attached tothe mounting plate ofthe rotor of a street sweeper; r V t :FIG. 2 shows .a fragmentaryvertical cross sectional view of the various elements of the broom in aposition ready for finalassembly; p FIG. fishows a fragmentary bottomview or the unitary clamping element in perspective 5.; ,EIG. 4shows afragmentary bottomview of the unitary broom back in perspective and; p VFIG. 5 shows 'a perspective View of the assembled broom mountedonthe've'rtieal rotor of a street sweeper. t Referring, tothe drawingswhere the same numbers are used to representthe various elements of thebroom and the rotor to which it is designed to be attached, it will beseen the broom compn'sesalunit-ary aluminum back having a unitaryannular brush section ztl clamped tothe back 10 by a unitary aluminumclamping element 30 releasably held in clamping relationby bolts 40extending through the back '10 and screwed into the clamping element 30.'As most-clearlyshown in FIGS. 1, 2, 4 and 5, the back '10 is provided adownwardly depending' flange 11 having avertical peripheral outer sidewall 12 and radial-inwardly extending fins 13. The unitary back isprovided with threaded steel inserts '14 cast thereinto for receivingthe bolts 50 whichfirmly attach the back of thebroom 10 tothe mountingplate 60 attached to the rotor shaft 61. The back i10,is alsotprovidedwith mounting pads 15, indenting lugs16,' a series of annular bolt holes177' for receiving bolts'40, and recessed portions 18 for receiving theheads 41 ofbolts 40 and the washers 42' used in association therewith. 1It will be noted the bolt holes -17 are located at a position removedfrom the a'xis'iof theibroomwandmin a peripheral region of the-top of-the, broom back relative to. theiaxis "or the broom. Due to thetorque-onthe-relatively large rotary brooms forstreet sweepers it isimpractical to clamp the brush material to the brush back-axially; i

The inside surface 19 of the flange 11 is curved so as to conformsubstantially to the natural curvature of the broom bristles when theannular section of crimped steel Wire Zttyis heldin clamping relation tothe back 10. It will be observed further that the radial fins 13 extendinto the annular section of brush material to the region of the lowerlip of the clamping element 30 where they function tohold the broom wirein a vertical position when the broom is in operation and, at the sametime, function to inhibit the rotation of brush material relative to thebroom back 10.

bell-shaped flange3-2 is provided with a series of threaded steelinserts 33 cast thereinto for receiving the threaded bolts 41). The clampingelement 30 -is provided with a suitable number of positioninglugs34so'that the clamp- .ing ring 21 can be readily centered over theclamping element 38' to facilitate assembly and with a plurality ofreinforcing ribs 35 which provide added strength to the clamping elementwithout requiring excessive weight. The unitary clamping element 30 isconstructed so that it; functions to' complement the functioning of theunitary back- 10 Thus in the assembled broom, when the annular sectionof brush material 20 is firmly clamped in place, the flat top surface 31comes in positive contact with the surface of positioning lugs 15 andthe lowerlip of the flange 3 2 is in. closeproximity to the radial fins'13 ofthe broom back 10 sothat the broom bristles will be separated intoa plunality of vertical sections by the nadial.fi=ns'.- 'In this way,the bristles are supported at the point wherethey leave the broomhousing yet they are not subjected toexce'ssivefatigue due to the factthe bristles are supported linearly by the radial fins and one anotherrather than being clamped, or supported, only at thepoint where theyleave the clamping ring.'

It will be seenthat some of the advantages of the radial fins nwhich.support the bristles and hold them in a vertical position could besupplied by outwardly extending radial fins on they clamping element 30rather than as inwardly extending radial fins on the broom back .10. itwill .be apparent, however, that the radial fins on the broom back.afford structural support for exposed flange ll'and aiford bettersupport for the bristles onthe outer periphery of the brush crown wheresupport is most needed'.

'As-best illustrated in FIGS. land 2, it can be seen the broom hereofmay be economically produced and easily assembled and disassembled inthe following manner.

, Firstly, the unitary aluminum broom back 10 and the complementaryunitary aluminum clamping element 30 are precast and the annular sectionof brush material 20 is preassembled in a manner disclosed above.Secondly, the clamping element 30 is positioned on asupport (not shown)and the annular ring 21 holding the annular section of brushmaterial ispositioned over the posi tioning lugs 34. ,Thirdly, the bolt holes 17 ofback '10 are aligned with the threaded steel inserts -33 of clampingelement 30 and boltsA-tl' inserted 'into bolt holes 17 supported onwashers 4:1 andfi-nitially screwed into thread-Y ed inserts 33'a'sFshowninfF IG Z.v .Finally the bolts are tightened until the flat top 31 'ofclamping element 30.

between a shoulder ofithe flange 31 of the clamping ele-. ment 3'0and'the inside face of the broom back 10 with jaw 24 restingcn the'shou1der of flange 32rand jaw 23 in contact'with' the inside face of thebroom back 10. If desired, once the broomis assembled the bolts 40 usedin assembling the broom may be replaced with shorter bolts to avoiddamage or breakage in use.

As shown, the annular top 31 of the clamping element 30 has an outerdiameter substantially less than the diameter of the inner face of thebroom back It so that when the annular section oi brush material 20 isheld in clamping relation with the broom back lit the bristles of thebroom are bent over a gradual curvature not placing an undue stress onthe bristles while at the same time contacting the curved inside surface19 of the broom back '10 over a wide bearing area. It will be apparentthat the outer diameter of the positioning lugs 3'4 of the clampingelement 30 and the curvature of the outwardly tapered inner surface 19of the flange 11. of the broom back may be selected in conformity withthe physical characteristics of the bristles contained in the annularsection of brush material 20 so that the composite objectives of ease ofassembly, proper sweeping angle for the brush material, and avoidance ofundue stress on the brush material are achieved.

The local indentations in the outer periphery of the crown brushmaterial imparted by the indenting lugs 16 are most clearly shown in theperspective view of an assembled and mounted broom in FIG. 5.

A rotary broom having the above disclosed features is very economical,assures ease of assembly and disassembly, has superior service life, andpermits thorough cleaning of street gutters without the danger of damageor breakage.

The bristles used in the brooms of this invention may be thoseheretofore used in the production of rotary brooms. However, in order toobtain the objectives of the invention, the brush material should bestill but flexible. Crimped steel wire has proven very satisfactory.Other materials such as straight steel wire, plastic filaments, etc.having these characteristics of stiffness and flexibility may also-hesuitable.

While the annular section of brush material is disclosed as a continuoussection, it will be apparent that discontinuous sections of brushmaterial, or tufts, could be provided which would be supported in avertical position in the manner described above.

It will be understood that flange is used herein to indicate a memberdepending from the annular broom back or from the annular back of theclamping element and providing a circumferentially continuous surfacetherebelow.

It will be obvious that the invention is not limited to the particularrepresentative structural elements shown in the drawings. Modificationsin the structural details adapted to achieve the objectives of theinvention will be apparent to those skilled in the art of producingrotary brooms (for street sweepers without departing from the spirit ofthe invention or its scope as defined in the appended claims.

What is claimed is: j

1. A rotary broom tor street sweepers, comprising a brush back having :adownwardly extending flange, clamping means underlying said back, meansreleasably holding said clamping means. to said back, an easilyremovable annular section of brush material having an inner portion ofcontinuous brush material clamped between said back and said clampingmeans and having other portions thereof passing through the spacebetween said flange and said clamp-ing means and extending downwardlyfrom the periphery of said flange, and means associated with said flangeand said clamping means and extending into said other portions of thebrush material vertically supporting it in the peripheral region of saidflange.

2. A rotary broom for street sweepers, comprising (a) a brush backhaving a downwardly extending flange provided with inwardly extendingradial means, (12) clampingmeans underlying said back extending intoproximity to other portions thereof passing through the space betweensaid flange and said clamping means and extending downwardly trom theperiphery of said flange.

, 3. A rotary broom for street sweepers, comprising a brush back havinga downwardly extending flange provided with peripheral inwardlyextending radial fins, clamping means underlying said back having adownwardly extending flange extending in proximity to said fins when inclamping position, means rel'easably holding said clamping means to saidback, an easily removable annular section of brush material having itsinner portion clamped between said b'ack' and said clamping means andhaving other portions thereof passing through the space between saidfirst flange and said clamping means and extending downwardly from theperiphery of said first flange.

'4. -A rotary broom for street sweepers, comprising a brush back havinga downwardly extending flange provided with outwardly tapered inner walland inwardly extending radial fins, clamping means underlying said backhaving a downwardly extending flange extending in proximity to said finswhen in clamping position, means releasably holding said clamping meansto said back, an easily removable annular section of brushmaterialhaving its inner portion clamped between said back and said clampingmeans and having other portions. thereof passing thnoughthe spacebetween said first flange and said clamping means and extendingdownwardly from the periphery of said first flange.

5. A rotary broom for street sweepers, comprising a brush back providedwith a downwardly extending flange having outwardly tapered inner walls,inwardly extending fins and substantially vertical peripheral outerwalls; clamping means underlying said back extending into proximity tosaid fins when in clamping position; means releasably holding saidclamping means to said back; an easily removable annular section ofbrush material having an inner portion of continuous brush materialclamped between said back and said clamping means and having otherportions thereof passing through the space be tween said flange 'andsaid clamping means and extending downwardly from the periphery of saidflange.

6. A back tor rotary brooms compnfsing a unitary annulus of light weightmetal provided with a flange having an outwardly flared and concavelycurved inner wall and inwardly extending radial. fins. V

7. A back tor rotary brooms comprising a unitary annular aluminumcasting having a flange with outwardly tapered concavely curved innerwalls, substantially vertical peripheral outer walls and inwardlyextending radial fins; said back having threaded insertsof harderdifiiculty deformable metal located in peripheral regions in the topthereof with respect to the axis of the broom back adapted to receivethreaded bolts for attaching the broom back to 'a mounting plate of arotor.

References Cited in the file of this patent UNITED STATES PATENTS FranceMay 9,1960

1. A ROTARY BROOM FOR STREET SWEEPERS, COMPRISING A BRUSH BACK HAVING ADOWNWARDLY EXTENDING FLANGE, CLAMPING MEANS UNDERLYING SAID BACK, MEANSRELEASABLY HOLDING SAID CLAMPING MEANS TO SAID BACK, AND EASILYREMOVABLE ANNULAR SECTION OF BRUSH MATERIAL HAVING AN INNER PORTION OFCONTINUOUS BRUSH MATERIAL CLAMPED BETWEEN SAID BACK AND SAID CLAMPINGMEANS AND HAVING OTHER PORTIONS THEREOF PASSING THROUGH THE SPACEBETWEEN SAID FLANGE AND SAID CLAMPING MEANS AND EXTENDING DOWNWARDLYFROM THE PERIPHERY OF SAID FLANGE, AND MEANS ASSOCIATED WITH SAID FLANGEAND SAID CLAMPING MEANS AND EXTENDING INTO SAID OTHER PORTIONS OF THEBRUSH MATERIAL VERTICALLY SUPPORTING IT IN THE PERIPHERAL REGION OF SAIDFLANGE.